Question
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Answer
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Who discovered that gravity actually makes all objects fall at the same rate?
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Galileo Galilei
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In the absence of air resistance and other external factors, what is the trajectory of an object's shape?
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A parabola
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Projectile motion, according to Galileo, has two separate and independant motions that superimpose each other, what are these two motions? (They are perpendicular)
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Horizontal motion
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Vertical motion
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What calculation is used to calculate acceleration in terms of final velocity, initial velocity and time?
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a=(v-u)/t
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What other three equations with 'a' can you use to find values for projectile motion? The first is in terms of final velocity (v)...
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v=u+at
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The second is in terms of v^2 (final velocity squared)... and r=displacement
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v^2=u^2+2ar
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The last is in terms of r...
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r=ut+1/2at^2
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If friction and other external forces didn't exist, when would an onject cease its horizontal motion?
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Never
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Therefore, when using the above equations for horizontal trajectory only, what single term does u (initial velocity) equal?
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v
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a=9.8m/s^2 ____ (because it is a vector).
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down
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Who theorised that if an object was thrown fast enough it would go into a permanent orbit?
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Isaac Newton
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What is the name for the velocity required to escape a planet's gravitational field?
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Escape Velocity
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The equation: Escape velocity = 2Gm(planet)/r(planet) is wrong. What is the right hand side missing?
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Square root
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What force provides the gradual upward lift needed for a rocket to launch?
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Thrust
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Along with the fuel, what must a rocket store for the engines to work?
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Oxygen supply
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What are the two most used states of propellant?
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Liquid
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Solid
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Which of Newton's Law's of Motion explain why a force of propelled gases downward force the rocket upwards?
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The third law
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The force of thrust must be greater than what other force before a rocket can lift off.
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Weight
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Although upwards thrust is constant, the acceleration of the rocket is never 100% and never constant either. What mass is decreasing which causes this to happen?
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The fuel's mass is burning away
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Since gravity also decreases as the rocket rises, what is the overall effect over time on the rocket's acceleration during its full launch?
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It increases
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What kind of increase does the velocity have?
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Logarithmic
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g forces are calculated using a division equation, normal true weight is the denominator. What is the numerator?
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Apparent weight
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How do you calulate apparent weight?
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mg+ma
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When dividing this equation by true weight, ma, the mass values cancel out leaving what equation?
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(g+a)/g
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Using simple maths, if an object is rising, its g force value will always be greater than what?
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One
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What direction would the object travel if the value of g forces was below this number?
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Downwards
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When in free-fall, what is the value of g forces experienced?
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Zero
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What types of rockets avoid excessive peaks in g forces?
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Multi-stage rockets
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The direction of what can be exploited to gain a boost in velocity when trying to reach orbit?
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The Earth's rotation
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